A wireless pulsed-current battery charger for implantable biomedical stimulators

Wireless battery charger for implantable biomedical devices (IMDs) with pulsed-current pattern is proposed for extending battery lifetime and faster charging. Also a compensation technique based on capacitor switching is presented in order to overcome the load variation effect on charging current. The data and power telemetry is separated in time domain and the power consumption is minimized during the Rest period in which just data are transmitted. The prototype of the system is implemented on the printed circuit board (PCB) and the measurements show less than 13% reduction in charging current. Overall power transfer efficiency is 34% and a 180 mAh Li-ion battery is charged by pulsed 26 mA current within 190 minutes.